Claims are on the up and up too – the docket for the future costs of all treatment injuries tallied $5.1 billion as of mid-2016.

Treatment injuries happen when people suffer personal injury during treatment from a registered health professional. The injury must have been caused by treatment, but not be a necessary part, or ordinary outcome of the treatment.

Last year, more than 1.1m people were treated and discharged from New Zealand's public hospitals.

During that time, ACC accepted 8881 claims from people harmed during the course of their treatment. Public DHB hospitals accounted for 59 per cent of those claims.

ACC publicly released the figures for the first time on Wednesday, in a report titled Supporting Patient Safety, in an effort to address the burden of treatment injury claims.

The report said the number of treatment injury claims had grown steadily since ACC cover was expanded in 2005 from medical misadventure to all treatment injuries.

International research estimates that up to 60 per cent of these injuries could be avoided or minimised.

But ACC's chief customer officer Mike Tully said some were unavoidable.

"For example, known medication side effects or skin burns from cancer radiotherapy. In both these examples, the severity and likelihood of known harm is weighed against the likely benefits of the treatment."

He agreed that some risk of patient harm was unavoidable, "particularly in situations where urgent and invasive treatments are being provided, and where people being treated have co-morbidities that increase risk".

"We can, however, work to minimise risk and the impact of any injury."

ACC would invest $45m in treatment injury prevention programmes across the health sector over the next five years, Rebstock said.

Only treatment injury claims from public DHB hospitals have been broken down in the report, but in future it will be expanded to include private hospitals, primary care, and other health service providers.

The cost of these claims is funded by workforce levies and Government funding.